Inductive radio transmission line

ABSTRACT

An inductive radio transmission line which is made of a plurality of pairs of two-wire transmission lines, each of which is formed in a plan view configuration upon a series of conductor supports, and each of the conductor supports is made of metal and has a configuration which closely surrounds the conductors of said line. Each pair of conductors of one two-wire line are repeatedly placed on the conductor supports and stretched in parallel therealong with any fixed number of said conductor supports and then transposed. The conductors of the transmission line are thus shielded from the outer field so that they are scarcely affected by the presence of foreign bodies such as rain, snow, soil and others.

United States Patent 1 1 Yoshida et al.

[111 3,809,796 [451 May 7,1974

[73] Assignee: Sumitomo Electric Industries, Ltd.,

Osaka, Japan [22] Filed: June 9, 1972 [21] Appl. No.: 261,384

[30] Foreign Application Priority Data June 12, 1971 Japan 46-41936 [52] U.S. Cl 174/33, 174/40 R, 174/147 [51] Int. Cl. H011) 11/02 [58] Field of Search 174/33, 34, 40 R, 146,

[56] References Cited UNITED STATES PATENTS 1,792,273 2/1931 Byk et al. 174/34 3,188,378 6/1965 Kitselman 174/147 X FOREIGN PATENTS OR APPLICATIONS 1,328,411 4/1963 France 174/147 1,128,165 8/1956 France 174/147 Primary Examiner-Hemard A. Gilheany Assistant ExaminerA. T. Grimley Attorney, Agent, or Firm-Carothers and Carothers 5 7] ABSTRACT An inductive radio transmission line which is made of a plurality of pairs of two-wire transmission lines, each of which is formed in a plan view configuration upon a series of conductor supports, and each of the conductor supports is made of metal and has a configuration which closely surrounds the conductors of said line. Each pair of conductors of one two-wire line are repeatedly placed on the conductor supports and stretched in parallel therealong with any fixed number of said conductor supports and then transposed. The conductors of the transmission line are thus shielded from the outer field so that they are scarcely affected by the presence of foreign bodies such as rain, snow, soil and others.

3 Claims, 5 Drawing Figures a F-rl-a INDUCTIVE RADIO TRANSMISSION LINE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an inductive radio transmission line formed upon a series of conductor supports of metal.

2. Description of the Prior Art A typical structure of a conventional inductive radio transmission line is shown in FIG. 1 in which the inductive radio transmission line consists of two-wire transmission linesl and 2, each respectively having spaced parallel conductors which cross each other or are transposed at a regular interval p.

One of said transposed two-wire lines is positioned in parallel with and overlies the other with a position shift of one half length of the transposition interval. Such an inductive transmission line is seen in the U.S. Pat. No. 3,527,897. Such an inductive radio transmission line has usually been made on a frame which is made, for example, of two parallel series of standing rods upon a plate of reinforced plastic. Accordingly, the electric lines of force between the two conductors of the transmission line-passthrough the reinforced plastic plate without any disturbance and they distribute broadly around the line.

If rain, snow, soil or sand covers such an inductive radio transmission line, it will greatly deteriorate the transmission properties of the line, because the electric field distributed around the line is affected by the presence of such material. Therefore, the radio communication system using a conventional inductive radio transmission line has the disadvantage that the reliability of the system is greatly reduced in accordance with the presence of such foreign bodies covering the line as rain, snow or soil.

SUMMARY OF THE INVENTION The object of the present invention is to provide an inductive transmission line which is scarcely affected .by the presence of foreign bodies covering the line. The inductive radio transmission line of the present invention has a number of conductor supports on which the transmission line is formed by placing the conductors in parallel therewith and each other, and transposing each pair of conductors at suitable intervals as measured by the positioning of the conductor supports.

According to the present invention, the transmission line can be manufactured and installed in the field in a simple manner placing the conductor supports in series at suitable intervals and then forming the line thereon.

BRIEF EXPLANATION OF THE DRAWINGS FIG. 1 is a diagrammatic plan view of a typical conventional inductive radio transmission line.

FIG. 2 is a diagrammatic plan view of the inductive radio transmission line of the present invention.

FIG. 3 is a perspective view of a conductor support used in the embodiment as shown in FIG. 1.

FIG. 4 is a view in cross section of a conductor sup port of the present invention.

FIG. 5 is a perspective view in partial section showing another embodiment of the conductor support of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An inductive radio transmission line of the present invention is shown in FIG. 2. In FIG. 2, numeral 1 denotes a two-wire parallel line transposed with a suitable interval p, and numeral 2 denotes another two-wire parallel line transposed in the same manner as two-wire transmission line 1. The two-wire line 1 is positioned in parallel to the other two wire line 2 and overlies it with a position shift of P/2. Conductor support 3 consists of a conductor frame having an insulation spacer with a plurality of grooves for supporting-the conductors of the transmission line.

Reference numerals 4 and 5 indicate the crossing points of the two-wire lines 1 and 2 respectively. The

conductor supports 3 are installed between adjacent crossing points 4 and 5 at a regular interval P/2. Twowi re transmission line 1 consists of conductors ll and 11', and two-wire transmission line 2 consists of conductors 12 and 12'. v

In FIG. 2, a number of conductor supports are installed in series at the interval P/2 where p is the transposing interval of the-two-wire line.

A pair of the conductors 11 and 11' are stretched in parallel along two adjacent conductor supports, transposed and repeatedly stretched in parallel along the successive two adjacent conductor supports so that the wiring loops formed successively by the transposed conductors provide the opposing and equivalent magnetic fields alternately.

Another pair of conductors 12 and 12' are installed alongthe conductor supports in the same manner as line 1, except that the transposing points 5 of the line 2 do not occur at the same places as the transposing points 4 and are shifted by one support such that the transposing points 4 and 5 occur alternately.

This inductive radio transmission line is energized by an exciter means which excites each of these two-wire lines independently with identical communication signals which have a phase difference of 1r/2 radians so that an antenna of a vehicle traveling along said line is capable of having a uniform receiving level thereby eliminating the effect of the transposition of two-wire transmission lines.

Another embodiment of the conductor support of the present invention is shown in FIG. 3. In FIG. 3, reference numeral 6 indicates a pair of metal frames having a channel part, and an insulator spacer 7 made of a synthetic material, for example, polyethylene, having several parallel grooves, which is placed in the channel part of the frame 6. Parallel grooves 8 are provided in the insulator spacer for supporting the conductors of two-wire transmission lines. Frame support9 is a metal plate firmly fixed to the pair of frames 6, and frame support rod 10 is a metal rod fixed firmly to frame support 9 and connected electrically to the ground. It is necessary that the conductor support 3 composed of the frame 6, frame support 9 and frame support rod 10 should be kept at ground potential.

The conductors 11 and 11' of the line 1 are supported by the conductor support 3. Conductor pair 12 and 12' of transmission line 2 are supported in the same manner.

Another type of conductor supports used in the transmission line of the present invention is shown in FIG. 4. In FIG. 4, frame 6 is formed of a metal plate 3 which entirely surrounds the conductors of two-wire lines. The remaining reference'numeral indicates the same objects as those. of FIG. 3.

FIG. 5 shows still another type of conductor support used in the present invention. In FIG. 5, metal frame 6 has several parallel grooves 13.

In this case, the conductors 11, ll, 12 and 12 of the lines must have insulator coatings 14 thereupon so as to insulate between the conductors and the frame. Other portions are numbered the same as the foregoing Figures.

The conductor supports as shown in FIGS. 3, 4 and 5 have a shielding effect in that the conductors of the line are electrically isolated from the outer field. Even though the transposing parts are exposed outside the conductor support, the affect of the generated field from the exposed transposed part is much smaller than the field generated from the non-transposed part of the line protected by the support.

In these support structures, the electric force lines between conductors of the two-wire line scarcely leak into the outer field and are collected on the surface of the metal conductor supports so that the electric force lines arenever distributed as broadly as those of the conventional lines which are not transposed at the same position, and they are scarcely affected by the present of the foreign bodies such as rain, snow, oils and other.

For the foregoing reasons, it is recognized that the inductive radio transmission line of the present invention has an excellent transmission property preventing the deterioration thereof due to the presence of the foreign matters around the transmission line.

In other words, the transmission line of the present invention has an excellent transmission property in spite of the presence of rain, snow or other forms of contamination.

It should be readily understood that it is possible to bury the transmission line of the present invention di- 4 rectly under the ground and to still have a good inductive radio communication system.

Another feature of the present invention is that the transmission line of the present invention is constructed and installed in the field in such a very simple manner. A number of conductor supports are installed in series with apredetermined interval and a pair of conductors of one two-wire line are stretched in parallel and transverse along the conductor supports for making an inductive transmission line and another twowire transmission line having a different transposing interval can be obtained easily by arranging the conductor supports at another suitable interval.

The inductive transmission line of the present invention has been explained in the case where a pair of twowire lines is in use.

However, the same explanation is applicable likewise to a system using three or more pairs of two-wire lines.

What we claim is:

1. An inductive radio transmission line comprising a layered plurality of pairs of two parallel wire transmission lines with each pair having successive wire transpositions at different locations from each other pair, a plurality of conductor supports of earth potential supporting said parallel wires, one of said conductor supports being positioned on each side of each of saidwherein said channels surround said conductors. 

1. An inductive radio transmission line comprising a layered plurality of pairs of two parallel wire transmission lines with each pair having successive wire transpositions at different locations from each other pair, a plurality of conductor supports of earth potential supporting said parallel wires, one of said conductor supports being positioned on each side of each of said transposition locations and having a frame with opposed parallel channels for receiving and supporting said parallel wires therein, and insulation means insulating said parallel wires from each other and from said frame.
 2. The inductive radio transmission line of claim 1 wherein said insulation means consists of a grooved insulator in each of said channels.
 3. The inductive radio transmission line of claim 1 wherein said channels surround said conductors. 